| dc.description.abstract | Winter wheat (Triticum aestivum L.) is widely used in the southern Great Plains as a winter forage resource to supplement income from a wheat monocrop system. Depending on production and prevailing market conditions, some producers may allow cattle (Bos Taurus L.) to graze wheat until the first-hollow-stem stage or to graze entirely. Thus, winter wheat offers dual benefits of grain and beef production in the form of three management systems: grain-only (GO, no grazing), forage only (full season grazing), or dual-purpose (DP, grazing and grain). Although traditionally, winter wheat cultivars are developed in GO production systems, they are often deployed in DP systems. The incidence and severity of soil-borne and insect transmitted diseases, insect herbivory, and abiotic stress are increased in DP system and thus can reduce grain yield depending on the year or cultivar. We hypothesized that a grazing system can be used as a selection tool to create breeding populations enriched with genes that confer grazing tolerance, persistence, and ultimately, improved adaptation. However, no clear evidence exists in wheat to refute or support this hypothesis. Thus, the main objective of this research was to determine selection responses in winter wheat induced by GO and DP management systems. Grain yield and associated traits for 24 sets of populations were measured in GO and DP systems, following natural selection in those systems for three consecutive generations (F2 - F4). Research was conducted in Marshall, Oklahoma using the F5 bulk progeny from each population. Our analysis showed that grain yield in a DP system can be increased by early-generation selection in that system, without negative consequences to grain yield in a GO system. | |
